Skin rash is an adverse reaction typical for anti-epidermal growth factor receptor (EGFR) therapeutics that is independent of tumor type.

Severe skin rash is associated with clinical benefit in cancer patients treated with cetuximab. The aim of this study was to verify whether CA simple sequence repeat in intron 1 (CA-SSR1) polymorphism is a predictive factor for skin rash and possibly for clinical response to cetuximab.

This study found that an increased number of CA repetitions was inversely associated with severity of skin rash as determined by body area covered; however, the association with clinical response was unclear.